1. Field of the Invention
The present invention is related to minimally invasive devices and methods for treatment of biological tissue. More particularly, the invention relates to underskin radiation treatment and removal of adipose tissue.
2. Invention Disclosure Statement
Nowadays, the abundance of readily available foods and sedentary lifestyle allow people to gain excessive weight by an increase in adipose tissue fat cells. Sometimes, this situation is enhanced due to certain hereditary conditions.
Excessive fat deposits or lipodystrophies are produced by a disproportionate increase in the deeper section of the subcutaneous cellular tissues. The only effective way to treat lipodystrophies is to directly act on the genetically altered fat tissues and similar tissues in the treatment area.
Historically, different methods have been developed to treat this condition, i.e., direct liposuction, ultrasonic liposuction, vibrational liposuction, laser lipolysis, laser lipolysis and suction and simultaneous laser lipolysis and suction.
Direct liposuction consists of the introduction into the adipose layers of probes roughly 5 mm in diameter through holes made in the skin of the patient undergoing treatment, for suction and removal of fat. This technique has a number of disadvantages, such as the in-homogeneity created in the zone of insertion of the probe, as well as excessive bleeding. Furthermore, both the cells of fat and the stroma are aspirated non-selectively. Several deaths have been reported because of the crudity of conventional liposuction.
Ultrasonic liposuction utilizes subcutaneous ultrasonic probes to rupture the membrane of the adipose cells, thus causing the escape of liquid which has to be aspirated out subsequently by vacuum means, much like in direct liposuction. Liposuction by ultrasonic means also produces connective tissue damage, so bleedings might occur as well. Furthermore, the lack of homogeneity resulting from the treatment still remains as a disadvantage.
Vibration liposuction uses a vibrating handpiece with an extraction channel integrated. Tissue is extracted by vacuum means and can be removed faster in comparison with the before-mentioned methods. However, connective tissue is still damaged, thus bleeding and other long term problems can occur. Another disadvantage is that vibrations of the handpiece can stress a surgeon's wrist. Therefore, it becomes difficult for surgeon to do precise work (e.g. suturing) after some time of treatment.
Laser lipolysis uses energy from a laser beam to liquefy the cells of the adipose layer. The liquefied fat is then carried away naturally by the lymphatic system or it can be removed by compression of remaining tissue. In U.S. Pat. No. 5,954,710, Paolini et al. disclose a device for the removal of subcutaneous adipose layers which comprises a first laser source, an optical fiber for conveying the laser beam emitted by said first source and a hollow needle for guiding the fiber, the fiber ending in the vicinity of the end of the needle. Preferably, the laser source has a wavelength ranging from 750 nm to 2500 nm. Pulse energy level is about 100 mJ in 200 μs of pulse duration, during a treatment time of a few minutes. Liquefied tissue can be removed by suction but is preferably left in place in order to be drained by lymphatic system and by action of phagocytes. According to the energy values mentioned previously, a high power laser source is required to perform treatment, leading to tissue carbonization, which may result in longer recovery periods, unsatisfactory results and patient discomfort.
In U.S. Patent Publication No. 2006/0253112A1, Suarez et al. disclose a method and device for cosmetic surgery, especially fat reduction and collagen reformation, by means of a high power laser operating at about 980 nm. The cosmetic surgery method substantially reduces or removes localized lipodystrophies, and essentially reduces flaccidity (at least 50%, due to fibro elastic retraction) by localized laser heating of adipose tissue using an optical fiber inserted into a treatment area. High power laser energy is applied through an optical fiber for breakdown of fat cells walls releasing the cell fluid. The optical fiber may be held within a catheter-like device having a single lumen and may have a diffuser mounted on the tip to further apply heating to tissues surrounding the whole tip. A saline solution may also be inserted into the treatment site to aid in the heating of the fat cells and their eventual destruction as well as their removal. The pool of cell fluid in the area of treatment is removed by a combination of techniques including: body removal by absorption and drainage from the entry sites (minimizing trauma), direct force application by means of elastic bandages and external suction applied to the entry sites. According to Suarez et al., treatment with the 980 nm laser was efficient and more suitable than traditional liposuction on up to 80% of the patients. Once again, as high power laser source is used to perform treatment, tissue carbonization can easily occur, which may result in longer recovery periods.
In U.S. Patent Publication No. 2006/0224148 Cho et al. disclose a device and related method for the removal of subcutaneous adipose layers comprising a laser source; an optical fiber for conveying a laser beam emitted by the laser source; and a hollow cannula for guiding the fiber to the subcutaneous treatment area. The cannula has a curved portion at its distal end, where the curved portion can be shaped to roughly conform to the contour of the patient's body structure. In this way, laser irradiation to lower dermis is generally avoided in curved body portions. Furthermore, a radiation detector or a temperature sensitive material is applied to the surface of the skin above the treatment area, in order to limit skin damage. Here again, tissue carbonization is the main action principle of this treatment.
In described previous prior art, since tissue removal is mainly restricted to the lymphatic system and compression of remaining tissue, only a low volume of tissue can be extracted effectively. Furthermore, the removal of liquefied adipose tissue via the lymphatic system can be insufficient and at times dangerous. In addition, as high power laser sources are used to perform treatment, tissue carbonization can easily occur, which may result in longer recovery periods, unsatisfactory results and patient discomfort.
An improvement to the previously mentioned techniques is performing liposuction after laser lipolysis, by utilizing a laser source to liquefy adipose tissue and then removing this tissue by means of a vacuum source. This method enhances the amount of liquefied tissue removal in comparison to laser lipolysis alone. However, as the removal of tissue is done after lipolysis, an ultrasound post-treatment is often necessary for the extraction of remaining tissue, increasing treatment time and cost and adding complexity to the process.
Another approach for performing improved liposuction is the simultaneous lipolysis and tissue extraction technique, which utilizes a laser source to liquefy adipose tissue and an extraction means for tissue removal in a substantially simultaneous way. In U.S. Pat. No. 6,464,694, Massengill discloses a liposuction cannula having a source of aqueous solution, a laser source, and a suction source. Aqueous solution is released into an active area within the cannula, and laser energy is directed onto the aqueous solution within the active area to energize the water molecules. The energized (hot) water molecules naturally escape from the active area into the surrounding fatty tissue to break down the fatty tissue and release liquid fatty material, which is removed by aspiration via the cannula. As can be seen, the device used in this invention does not apply laser energy in a direct way, so the amount of energy delivered can be difficult to quantify and can lead to unspecific tissue radiation.
Other patents claim devices disclosing removal of fat, liquefied by means of direct laser energy. In U.S. Patent Publication No. 2007/0219540A1, Masotti et al. claim a device for skin tightening which comprises a hollow cannula that contains an optical fiber connected to a laser source. The cannula is inserted subcutaneously into a patient so that the end of the fiber is located within the tissue underlying the dermis. The source emits an output pulse that is conveyed by the fiber to the dermis, where the pulse causes collagen destruction and shrinkage within the treatment area. In U.S. Pat. No. 7,060,061, Altshuler et al. claim a device for targeting lipid-rich tissue where probe includes a cannula through which liquid fat formed as a result of the irradiation ablating tissue walls is removed. In U.S. Patent Publication No. 2008/0188835A1, Hennings et al. claim a handpiece and method of use for laser-assisted liposuction for inciting, disrupting, and removing cellulite and adipose tissue.
It can be seen in mentioned prior art, where tissue is removed by vacuum means, irradiation as well as aspiration is carried out by inserting needle lumen which serves as a channel both for conveying laser energy by means of inserting optical fiber and for aspirating excess tissue. As a consequence, effective lumen is reduced by the presence of optical fiber when lasing. Therefore fat tissue can clog hollow needle, rendering simultaneous irradiation and aspiration difficult or even impossible. Thus, in order to achieve an effective treatment, irradiation and aspiration should be done sequentially, also leading to a longer procedure. Another disadvantage is that, optical fiber is confined inside hollow cannula thus leading to numerous limitations. In first place, the laser beam that emerges is focalized on a small area and at higher energies it may carbonize the tip and the tissue. In second place, optical fiber used must have a frontal emission pattern, limiting treatment possibilities. Furthermore, they do not include means for irrigation of fat tissue in order to make the procedure more efficient.
Summarizing, as can be seen from afore-mentioned prior art, even when irradiation and suction can be performed practically simultaneously, conventional laser liposuction approaches utilize high laser energy sources for irradiation of tissue to be treated. For instance, in the previously mentioned patent by Paolini, laser energy of 100 mJ is delivered in pulses of 200 μs, resulting in the high power/pulse value of 0.5 KW. These techniques are aimed at applying most of this high energy directly on adipose tissue, which may result in tissue carbonization. Tissue carbonization leads to longer recovery periods, unsatisfactory results and patient discomfort. Furthermore, since irradiation and aspiration are carried out through the same channel, its effective lumen is reduced by the presence of optical fiber when lasing, leading to inefficient fat extraction. In addition, since optical fiber is confined inside hollow cannula, some limitations arise: small focalization area of the laser beam which may carbonize the tip and the tissue; optical fiber must have a frontal emission pattern, limiting treatment possibilities. Finally, they do not include means for irrigation of fat tissue in order to make the procedure more efficient.
Due to the disadvantages and deficiencies of current liposuction techniques, a need exists for a device that provides a fast and safe alternative to address their shortcomings.